Two thirds of the Earth’s surface is covered by oceans, which represent one of the ultimate frontiers for discovery, science and technology. Remotely operated underwater vehicles (ROVs) and autonomous underwater vehicles (AUVs) have become essential tools in the exploration of aquatic environments. Such underwater vehicles characterise areas by means of large volumes of sensed data, which are in turn either stored on-board the vehicles, at a significant cost to the battery life, or sent elsewhere underwater via communication links. At present, the latter utilise tethered optical fibres or wireless acoustic communications. However, tethered links restrict mobility and acoustic systems lack the bandwidth to support high speed communications. As a result, underwater optical wireless communications (UOWC) have become of increasing interest in recent years.
This talk will introduce the topic of underwater communications and the place for UOWC within this. An overview of the propagation of light underwater will be given, including attenuation and scattering. The characteristics of the aquatic medium, including the major water types and their influence on UOWC system design will be presented followed by a summary of some established systems.
Finally, recent results from the Connected Systems Group will be presented. These will focus on the prediction of spatial diversity in a multiple input multiple output (MIMO) system and non line of sight UOWC.